Health officials have added eight new substances on the official U.S. list of toxins known to cause or suspected of causing cancer, which includes the widely used chemical formaldehyde.
Government scientists listed formaldehyde as a carcinogen, and said it is found in high quantities in plywood, particle board, mortuaries and hair salons. Lab results showed formaldehyde caused nasal cancer in rats when tested, according to a report issued by the U.S. Health and Human Services.
They also said that styrene, which is used in boats, bathtubs and in disposable foam plastic cups and plates, may cause cancer but is generally found in low levels. But the greatest exposure to styrene in the general population is through cigarette smoking.
“Substances and exposures that can lead to cancer are called carcinogens,” according to the American Cancer Society. Scientists get much of their data about whether something might cause cancer from lab studies in cell cultures and animals.
"There is now sufficient evidence from studies in humans to show that individuals with higher measures of exposure to formaldehyde are at increased risk for certain types of rare cancers, including nasopharyngeal and sinonasal cancer, as well asmyeloid leukemia," according to HHS.
Formaldehyde is a widely used colorless, strong-smelling chemical that is also used to make resins for household items such as composite wood items, plastics, and textile coatings. It's also commonly used in medical laboratories, nail polish, and in hair straightening products.
Some say the smell is similar to that of a new house.
Another new substance on the carcinogen list is aristolochic acids, which are used in a variety of herbal products often sold on the Internet and abroad to treat conditions such as arthritis, gout, and inflammation. The substance caused high rates of bladder or upper urinary tract cancer among people with kidney or renal diseases.
The six other substances include Captafol, which is a fungicide used to control fungal diseases in fruits, vegetables, ornamental plants, and grasses, and as a seed treatment. It has been banned in the United States since 1999, but past exposures may still have an effect on health, according to health officials.
Next on the list is Cobalt-tungsten carbide, a substance commonly referred to in the United States as cemented or sintered carbide. The substance is used to make cutting and grinding tools, and wear-resistant products for various industries, including oil and gas drilling, as well as mining.
Certain inhalable glass wool fibers were also tested and added to the list. The fibers can enter the respiratory tract and remain in the lungs for long periods of time. The largest use of general purpose glass wool is for home and building insulation.
Lab results showed o-nitrotoluene contains human carcinogens and is used in dyes, including magenta and various sulfur dyes for cotton, wool, silk, leather and paper. The substance is also used in preparing agricultural chemicals, rubber chemicals, pesticides, petrochemicals, pharmaceuticals and explosives.
Riddelliine is also dangerous and found in certain plants of the genus Senecio, a member of the daisy family. Some derivatives of this substance are found in herbal medicines and teas.
Styrene, a synthetic chemical used worldwide in the manufacture of products such as rubber, plastic, insulation, fiberglass, pipes, automobile parts, food containers and carpet backing caused alerts for carcinogens.
"Reducing exposure to cancer-causing agents is something we all want, and the report on carcinogens provides important information on substances that pose a cancer risk," said Linda Birnbaum, director of both the National Institute of Environmental Health Sciences and the National Toxicology Program.
There are now 240 substances listed with the agency that are known carcinogens.
Health officials say a listing in the report on carcinogens does not by itself mean that a substance will cause cancer.
“Many factors, including the amount and duration of exposure, and an individual's susceptibility to a substance, affect whether a person will develop cancer,” according to the ACS.
Although it isn't possible to predict with certainty which substances will cause cancer in humans based on lab studies alone, virtually all known human carcinogens that have been adequately tested produce cancer in lab animals.
In many cases, carcinogens are first found to cause cancer in lab animals and are later found to cause cancer in people.